A multiple-input multiple-output (MIMO) technology is a hot research topic at present in the wireless communications field. The MIMO technology is used in various new mobile communications systems to increase spectrum efficiency of the systems. The MIMO technology may increase a space dimension of data multiplexing, so that a same time-frequency resource is spatially reused by multiple pieces of data; and may also use multiple transmit antennas to send same data and/or use multiple receive antennas to receive same data, so as to obtain space diversity gain. A typical space diversity technology includes Alamouti space time block code (STBC), and a typical spatial multiplexing technology includes a vertical Bell Labs layered space time (V-BLAST) technology.
FIG. 1 is a schematic diagram of an application scenario of MIMO detection. As shown in FIG. 1, a transmit end transmits a transmit signal by using a transmit antenna, and a receive end receives the signal by using a receive antenna and detects the transmit signal by using the MIMO technology, where the transmit signal may be represented by using a transmit signal vector. That is, a basic feature of the MIMO technology is multiple transmit antennas and multiple receive antennas. It is assumed that a quantity of transmit antennas is MT, and a quantity of receive antennas is MR, a MIMO transmission model may be represented as:
                                          [                                                                                y                    1                                                                                                                    y                    2                                                                                                ⋮                                                                                                  y                                          M                      R                                                                                            ]                                ︸            Y                          =                                                            [                                                                                                    h                        11                                                                                                            h                        12                                                                                    …                                                                                      h                                                  1                          ⁢                                                      M                            T                                                                                                                                                                                                  h                        21                                                                                                            h                        22                                                                                    …                                                                                      h                                                  2                          ⁢                                                      M                            T                                                                                                                                                                          ⋮                                                              ⋮                                                              ⋱                                                              ⋮                                                                                                                          h                                                                              M                            R                                                    ⁢                          1                                                                                                                                    h                                                                              M                            R                                                    ⁢                          2                                                                                                            …                                                                                      h                                                                              M                            R                                                    ⁢                                                      M                            T                                                                                                                                              ]                                            ︸                H                                      ⁢                                          [                                                                                                    s                        1                                                                                                                                                s                        2                                                                                                                        ⋮                                                                                                                          s                                                  M                          T                                                                                                                    ]                                            ︸                S                                              +                                    [                                                                                          n                      1                                                                                                                                  n                      2                                                                                                            ⋮                                                                                                              n                                              M                        R                                                                                                        ]                                      ︸              n                                                          (        1        )            or it may be briefly recorded as Y=Hs+n where yi is a signal received on the ith receive antenna, Y is a received signal vector that includes a received signal, hij is a channel response between the ith receive antenna and the jth transmit antenna, H a channel matrix, sj is a data symbol sent on the jth transmit antenna, s is a transmit signal vector that includes a data symbol sent on a transmit antenna, ni is noise received on the ith receive antenna, and n is a noise matrix.
The transmit signal vector s may be detected by using the MIMO detection. When the quantity of receive antennas is no less than a quantity of transmit symbols, the receive end can suppress or eliminate interference among multiple transmit symbols as much as possible by using a MIMO balancing algorithm, so as to restore MT transmit symbols. A common linear MIMO balancing algorithm includes a linear minimum mean square error (LMMSE), zero forcing (ZF) and the like. In addition, the receive end may also consider all the MT transmit symbols as a complete codeword, and use a maximum likelihood detection (MLD) method to perform detection, so as to estimate the MT transmit symbols. The MIMO balancing algorithm together with successive interference cancellation (SIC) may also be used for receiving, that is, a transmit symbol thereof is estimated by using the linear MIMO balancing algorithm, and then the transmit symbol is eliminated as known interference and another transmit symbol is estimated by using the linear MIMO balancing algorithm. Sequential iteration is performed until all the transmit symbols are detected and received.
In all MIMO detection algorithms, an MLD algorithm has the best performance, but in higher order MIMO, the MLD detection algorithm has a very high complexity and is difficult to implement in a product in practice; therefore, the prior art lacks a detection method with good performance and low complexity.